Once you are done actioning your email and it's attached to a contact, work or in a to-do list, you should clear it from triage.
Option 1: click on the Clear icon from your email actions menu
Option 2: Click on the Assign & clear icon directly after you have assigned the email to yourself or a colleague
What happens to the email in your account? When an email is cleared from Triage, it will be archived in your Gmail or O365 inbox.